Abstract: To explore the difference in nitrogen efficiency of alfalfa and the underlying mechanism,8 alfalfa varieties ('LW6010','Gannong No.5','Gannong No.3','Xinmu No.1',and'Gannong No.7'and'Longmu 801','Longdong alfalfa'and'Golden Queen') were sand-cultured using nutrient solution with 3 levels of nitrogen (21 mg·L^-1,210 mg·L^-1,420 mg ·L^-1).The growth characteristics and related indicators of nitrogen fixation,absorption,and transformation characteristics were analyzed.Principal component analysis were performed to explore the effects of the above characteristics on nitrogen efficiency.The results showed that:under low nitrogen,suitable nitrogen,and high nitrogen,the growth characteristics,nitrogen fixation,absorption and transformation characteristics of nitrogen-efficient alfalfa ('LW6010','Gannong No.5') were better than those of nitrogen-low-efficiency lavender alfalfa ('Longdong alfalfa'and'Golden Queen'),while the nitrogen norms ('Gannong No.3'and'Xinmu No.1') and nitrogen inverse effects ('Gannong No.7','Longmu 801') were somewhere in between,and behaved the opposite under different nitrogen levels.According to the comprehensive evaluation of the membership functions,the comprehensive values of the membership functions of'LW6010'and'Gannong No.5'reached the maximum;principal component analysis showed that the number of nodules and the weight of nodules contributed the most to the nitrogen efficiency of alfalfa,reaching 8.82% and 8.43% respectively.

Key words: Alfalfa, Nitrogen efficiency, Difference mechanism

摘要： 为探讨紫花苜蓿氮效率差异及其差异机制,以8个紫花苜蓿品种('LW6010'、'甘农5号'、'甘农3号'、'新牧1号'、'甘农7号'和'龙牧801'、'陇东'苜蓿和'金皇后')为试验材料,采用营养液砂培法,设3个氮水平(21 mg·L^-1,210 mg·L^-1,420 mg·L^-1),测定其生长特性和氮素固定、吸收及转化特性相关指标,并采用主成分分析法来探讨以上特性对氮效率的影响。结果表明:低氮、适宜氮和高氮下,氮高效型紫花苜蓿('LW6010'、'甘农5号')的生长特性和氮素固定、吸收、转化特性均优于氮低效型紫花苜蓿('陇东'苜蓿和'金皇后'),而氮常效型紫花苜蓿('甘农3号'和'新牧1号')和氮反效性紫花苜蓿('甘农7号'、'龙牧801')则介于二者之间,且在不同氮水平下表现相反;又根据隶属函数综合评价,'LW6010'和'甘农5号'的隶属函数综合值达到最大;主成分分析表明,根瘤数和根瘤重对紫花苜蓿的氮效率贡献率最大,分别达到了8.82%和8.43%。

关键词: 紫花苜蓿, 氮效率, 差异机制